From the street in front of the grey bungalow on Walnut Avenue, there are few clues to what took place over the course of 18 years in the anonymous shed hidden at the back of the property.

The compound of outbuildings and tents where Jaycee Lee Dugard's long imprisonment played out is barely visible, obscured by a thin white fence wrapped in barbed wire – and beyond it a chaotic, ramshackle yard. Behind a vast tarpaulin that hid her from the outside world for two decades, Dugard was held, along with the two children she had by her abductor, Phillip Garrido.

Navigating the abandoned junk and disused bicycles that litter the area, police combed the area for evidence of the kidnapping and abuse.

Through the bungalow's windows — screened to keep out flies through the heavy summer heat of this stretch of California – the house appears uncared for. After years of neglect and the diligent searches of local police officers, the floor is strewn with boxes and debris."

Keeping such a terrible secret for so long is not outside the bounds of imagination given the hushed surroundings of Walnut Avenue. In a dusty corner of Antioch – a commuter town 45 miles east of San Francisco – it is the kind of place where people go to indulge their hobbies and stay away from the crowds.

It is an area of California used to discovering that the truly bizarre is taking place on its doorstep – not least through the 1970s, when San Francisco played host to cult leaders including Charles Manson and Jim Jones.

The Garridos' neighbours have largely retreated into their homes to keep clear of the police and media.

One local, who asked not to be named, said she used to live directly behind the yard where Dugard was held in captivity. "She was no more than 30 yards from my dumpster; my children would play out in the street. But nobody ever knew," she said. "It's quiet there, very quiet – nobody ever goes there unless they have some reason to."

She held "typical grocery store conversations" with Garrido when he dropped into the supermarket where she worked, sometimes two or three times a day. "How he walked around town knowing what he was doing to that girl I don't know."

Doris Mangrum, an author and film-maker who has lived in town for 13 years, said some had concerns about Garrido's behaviour, but it was impossible to divine what was taking place under their noses.

"While some people had some uneasiness about him, nobody had a clue what was really going on," she said. "Antioch is generally quiet, but we're beginning to see more urban-type crime."

In the centre of Antioch itself – a long, straight road bordered by strip malls and lonely shops, the orderly procession of day-to-day life is in sharp contrast to the chaos nearby.

Most of the 100,000 people in this fast-growing town conduct an hour-long pilgrimage every day to their jobs in San Francisco and Oakland.

For the locals, life continues as usual. In a coffee shop, patrons shrug their shoulders when asked about the events that took place just a few hundred yards away – this is, they say, a part of the world where people like to keep their private business to themselves.